1. Field of the Invention (Technical Field)
The following description relates to the field of optical telecommunications using tunable external cavity diode lasers. The ability of this invention to operate at discrete wavelengths corresponding to optical telecommunication channels without add-in optical components greatly improves the utility of the device while providing substantial cost savings.
2. Background Art
Diode lasers have become enabling technology for fiber optic networks (telecommunications) because of their cost, compactness, and spectral properties. External cavity lasers (ECLs) based around diode laser gain elements are further enhancing capability in these applications by virtue of their excellent spectral properties with significantly increased wavelength tuning ranges. It is essential to exploit the increased spectral coverage of ECLs while simultaneously insuring that they operate only at precisely defined communication channels (wavelengths). This requirement is typically accomplished by the incorporation of add-in optical components that ‘lock’ the ECL output wavelength to these specifically allowed channels. Such add-in components contribute substantially increased cost to the ECL source laser. Furthermore, the optical alignment of these components to achieve the required wavelength precision is nontrivial and may incur substantial production costs. In the worst case, the optical alignment of these add-in components would require human interaction. The present invention relies on extant features of already-included ECL components, slightly modified, to provide their normal functions while simultaneously providing the required discrete wavelength locking. Thus, add-in optical components and their associated alignment requirements are eliminated.